Begin by lining two baking sheets with parchment paper and preheating your oven to 300°F (150°C). Organize your ingredients and tools.

In a clean mixing bowl, whip room-temperature egg whites on medium speed until foamy. Gradually add granulated sugar and increase to medium-high until stiff peaks form.

Sift together almond flour and powdered sugar, then gently fold into the meringue until the batter flows like lava; about 30 strokes.

Fill a piping bag fitted with a round tip and pipe even circles onto prepared baking sheets, approximately 1.5 inches in diameter.

Let the piped macarons rest for 30-60 minutes until the tops are dry to the touch.

Bake the macarons in the preheated oven for 12-15 minutes, ensuring they have risen and developed a smooth top.

After baking, cool the macarons on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.

Once cooled, pair similar-sized shells and pipe blackberry filling onto the flat side before gently pressing the top shell on.